XmlParser: case-insensitive accept for nuget.config (#7317)

* Use case-insensitive comparison for nuget.config and packages.config in XmlParser

The XmlParser.accept() method used Path.endsWith() which is case-sensitive,
so files like NuGet.config or Packages.config were not recognized as XML and
fell through to the PlainTextParser. Switch to equalsIgnoreCase on the file
name to handle all casing variants.

* Also make file extension checks case-insensitive in XmlParser

Apply toLowerCase() to the extracted extension before checking against the
accepted set, so files like foo.XML or proj.Csproj are correctly recognized.

Author: steve-aom-elliott

rewrite-xml/src/main/java/org/openrewrite/xml/XmlParser.java

@@ -117,12 +117,13 @@ public boolean accept(Path path) {
         String p = path.toString();
         int dot = p.lastIndexOf('.');
         if (0 < dot && dot < (p.length() - 1)) {
-            if (ACCEPTED_FILE_EXTENSIONS.contains(p.substring(dot + 1))) {
+            if (ACCEPTED_FILE_EXTENSIONS.contains(p.substring(dot + 1).toLowerCase())) {
                 return true;
             }
         }
-        return path.endsWith("nuget.config") ||
-                path.endsWith("packages.config");
+        String fileName = path.getFileName().toString();
+        return fileName.equalsIgnoreCase("nuget.config") ||
+                fileName.equalsIgnoreCase("packages.config");
     }
 
     @Override

rewrite-xml/src/test/java/org/openrewrite/xml/XmlParserTest.java

@@ -686,9 +686,15 @@ void preserveWhitespaceOnEntities() {
     @ParameterizedTest
     @ValueSource(strings = {
       "foo.xml",
+      "foo.XML",
       "proj.csproj",
+      "proj.Csproj",
       "/foo/bar/baz.jsp",
-      "packages.config"
+      "packages.config",
+      "Packages.config",
+      "nuget.config",
+      "NuGet.config",
+      "NuGet.Config"
     })
     void acceptWithValidPaths(String path) {
         assertThat(new XmlParser().accept(Path.of(path))).isTrue();